close() 会永久地锁定 PGlite 并阻塞事件循环

If `close()` is called while a statement issued earlier is still in flight, **neither promise ever settles** — the statement never resolves or rejects, and `close()` never returns. The process is left permanently wedged. Depending on where in the protocol exchange the backend was deactivated, it either spins at 100% CPU inside `execProtocolRawSync`'s synchronous main loop or blocks at 0% CPU.